XeMODeX, or stay on the Volvo ETM path?

[BobbyC]

I recently posted a thread called "My S60s at the dealership now" about my 2001 S60 T5 w/ 105,000mi
( https://www.matthewsvolvosite.com/forums ... 12&t=38365 ), and I have now retrieved my vehicle from the dealership.

I gave them a VERY complete written (long typed page) precise description of the hesitation/surge I was having, and what would trigger it, and delivered the car w/ an "Engine Service Required" message still showing.

After several days, they called and said that they replaced the fuel pump under a Campaign Recall 220, but could not duplicate the surge/hesitation, even when a tech took the car and used it for several days as his personal vehicle (they did ask permission) putting a few hundred miles on it.

I drove to the dealership (30mi) and one of their techs drove the car with me, and then I drove w/ him observing, and sure enough, for the first time in a YEAR, it had so little surge/hesitation I almost couldn't feel it myself (and the tech couldn't feel it at all). He said maybe the problem had been the fuel pump, but a thorough scan and ETM test showed NO problems at all except the Brake Diaphragm Sensor Fault (I have since replaced the sensor).

So I returned home and got a ride to the dealership and picked up my car. Wouldn't you KNOW that about 1/2 way home it started acting up again. The idle is dead smooth, and under stiff acceleration, the car goes like a bandit like always. The ONLY time it is a PITA is under slight acceleration, or while climbing a hill. (worse if car is heat soaked, or if A/C is on)

Slight acceleration, or trying to maintain speed up any hill (there are NO hills near the dealership or the tech's home, so they could not try this test) causes the car to surge/hesitate like you are getting hit by really strong gusts of wind, and the RPM will vary by 50rpm or so when the torque converter is not locked up (and just a "feeling" if it is). This is true in cruise control, or if I use the throttle manually.

If I set the parking brake and increase the throttle, the RPM will vary like I am modulating the throttle pedal up/down.

I bought a scan tool (Innove 3160) capable of reading "Live Data" to see maybe what was actually varying, and it confirmed during the surge/hesitation the 50rpm variation seen on the tach. The O2 voltage also varied pretty fast from 0.105 to 0.735 (one sweep to the next), and the throttle position (TPS) changed from 22% to maybe 24% (2% variation), or 19 to 21 (still 2%), depending where the throttle was held during acceleration or uphill. The MAF (measurement of the airflow) would also vary by around 10% with the throttle pedal held constant, which makes sense if the ETM throttle plate is moving around. Everything else I could measure (Spark Advance, Intake Air Temp, Coolant Temp) read steady or correctly. My scan tool is capable of more parameters, but evidently Volvo does not support most of them.

The extremely rapid O2 sensor value changes, and the magnitude of them seemed odd. Also, Should I expect the actual throttle position to vary a bit (that 2%) even w/ the throttle pedal held firm because of the vehicle computer since it's an active feedback loop? OR should the TPS remain constant just as if the butterfly were connected to the pedal with a cable? The Volvo dealer told me the '99-'01 ETMs talk back and forth w/ the computer, allowing the computer to move the butterfly independent of the actual throttle pedal, whereas later models ONLY respond to the throttle pedal just like a solid linkage, and don't have the 2-Way communications of the earlier ones like mine.

The Tech also suggested changing all of plugs and my coil packs, since even though mine are only 15,000mi old, they tend to fail regardless. Wouldn't I feel a "hard miss" under hard acceleration if a coil pack were bad? He couldn't answer that one. I hesitate to spend $300 for new plugs and coil packs w/out some more evidence. Wouldn't a bad coil pack be recorded as a "misfire" and set a DTC (MIL light)?

He admitted that MAYBE I have a bad ETM, but without any of the accepted "death codes" Volvo won't authorize any work on the car. He also said cleaning the ETM probably would do no good since my car does have such a smooth idle (which it returns to each time the throttle is released).

Sorry for the long post, but this is obviously driving me nuts!

Maybe my latest data from the scanner adds some clues for some of you out there? Anything different I can try to make the problem more obvious?

Thanks,
Bob
BTW, My scan tool has a feature allowing it to do an O2 test using data saved in the car's ECM, but unfortunately Volvo does not support this function.

[precopster]

I've read afew posts about very similar cicumstances in other cars. You may have to wait until total failure of the contact strip area which is causing the problem. (sounds like there's only one portion of the strip worn in your case)

As far as the coil packs go there is often physical evidence of arcing at the coil pack body (white powdery marks) which are a sign of impending failure. Is this the case on the sides of your packs? Often DTCs don't show.

A smooth idle is NOT always an indication of a good ETM. Cleaning the ETM may yield very good results. Many owners have done this and found that flat spots have gone. It's no different from any other throttle body in that the gases require smooth internal surfaces to flow against.

Have a look at this link:

It may offer some help

[JRL]

Really not the forum for this...yet
Have you tried a new MAF sensor?

[BobbyC]

I was told sometimes the coil packs break down internally a bit (though normally I'd expect such a breakdown to affect things under high load rather than light load), and to get a couple and start substituting them until all 5 have been replaced at one point to see it it runs well, so I ordered a couple.

It looks like pulling the ETM on the T5 is a hassle with all of the crap there, and I have hesitated only because recent back surgery makes contorting uncomfortable, but I'll put that on the list.

You mention, "You may have to wait until total failure of the contact strip area which is causing the problem. (sounds like there's only one portion of the strip worn in your case)." I guess it makes sense the part of the film where the contacts ride MOST of the time will give trouble first, and that's probably right where I am having the problem. Since I have no MIL or DTC codes, I guess it has to be REALLY bad before they set a code.

I thought it strange it ran almost perfectly after a fuel pump change, making me wonder about a fuel or fuel pressure problem, but the regulators in w/ the pump in the tank on the S60, but I can still measure the pressure at the fuel rail, though I wouldn't think it would just affect partial throttle.

I saw that S80 YouTube, though he had the more typical idle problem as well.

Thanks,
Bob

[BobbyC]

Really not the forum for this...yet
Have you tried a new MAF sensor?

Sorry if I am posting in in the wrong forum.

I kind of figured I had an ETM problem when I first came here, but maybe until it is fully diagnosed I should go elsewhere to do troubleshooting. My apologies if that's the case. I will look for a more appropriate Forum for any further new threads.

You mentioned the MAF. I cleaned it previously w/ a MAF Cleaner Spray, and I don't know if there's a way to test it, so I just ordered a new one.

I know the dealer said unless they get codes, they don't even bother troubleshooting anything until things get so bad that there ARE DTCs displayed, but the car is so miserable to drive, I hate to live with it long enough to throw a code I guess.

Bob

[kcodyjr]

If you drove it like you stole it, think it might set a code? Just a thought.

[BobbyC]

If I drive it like I stole it, it GOES like Hell, smooth as anything. No codes.

Only bucking is present over a fairly narrow throttle range right what it takes to maintain speed up a slight grade, or to accelerate gradually. I'm starting to wonder if the resistor film is going where it spent most of its life moving about. My scan tool showed the hesitation/stumble were worst at about 18-24% throttle position in Live Mode.

Idle and aggressive throttle are impressively smooth.

Thanks-
Bob

[petermetzger]

Have you determined anything about what was going on?

I just bought my first Volvo yesterday (Silver 1999 V70 T5 w/ 98K miles) and I was going to start a thread about the one odd symptom it exhibits... but it looks like you're having almost exactly the same issue. Like yours, mine idles perfectly and runs very smoothly while accelerating or slowing down (and goes like a bandit if you really step on it )

My issue, which doesn't *always* happen, is hesitation or the feeling of a gusty wind hitting the car when I'm maintaining a constant speed. I haven't noticed for sure if it happens more when I'm going slightly uphill, but I think you may be right. I'll take it out for a drive today and see if I notice any correlation.

The first time I got it to go away, I let the car slow down a bit then gave it some gas to return to normal speed. After that it was fine for the rest of the 2-hour trip. However, the problem returned for parts of the 1.5 hour trip I took later that night, and the previous fix (besides being rather inefficient) didn't always take care of it.

As a side note, I knew going into it that this problem might require a new ETM and figured that into my buying price.

Any ideas?

[BobbyC]

I finally ended up with a new ETM and that cured the problem completely.

Other things I tried (recommended here and by the tech at the dealership who test drove the car w/ me) were new coil packs, plugs, and MAF sensor, but they didn't help at all.

Bob

[petermetzger]

Did you replace with a Volvo ETM or one of the aftermarket ones?